Association of Preadmission Metformin Exposure and Outcomes in Acute Kidney Injury Patients with Type 2 Diabetes in Intensive Care Unit: a Cohort Study

Abstract Background: Acute kidney injury (AKI) occurred in more than half of ICU patients. The effective prevention and therapies strategy of AKI remains limited. This study is to assess AKI mortality among diabetes patients with or without preadmission prescriptions for metformin. Methods: We included AKI patients with type 2 diabetes in Medical Information Mart for Intensive Care (MIMIC)-III database. 30-day mortality, neutrophil-to-lymphocyte ratio, and length of stay (LOS) in the hospital were compared between those with and without preoperative prescriptions. The statistical approaches included multivariate regression, propensity score analysis and an inverse probability‑weighting model to ensure the robustness of our findings. Results: In total, 4328 AKI patients with type 2 diabetes (998 in preadmission metformin usage group and 3330 in no preadmission metformin usage) were included in the analysis. The overall 30-day mortality was 14.2% (613/4328). There was 15.7% (523/3330) and 9.0% (90/998) of 30-day mortality in no preadmission metformin usage and preadmission metformin usage group, respectively. In the main analysis, preadmission metformin usage was associated with a 37% lower of 30-day mortality (HR=0.63,95% CI:0.50-0.80, p<0.0001) in inverse probability‑weighting model. Conclusions: This cohort study suggested that preadmission metformin usage may be associated with reduced risk-adjusted mortality in AKI patients with type 2 diabetes. Further randomized controlled trials are needed.